In recent years, not only asbestos scattering in spray work but also decaying, degrading, and detaching and scattering after spraying have caused large problems, and asbestos pollution has become a significant problem. That is, asbestos that is light-weight and fine easily scatters in the air. Asbetos has a spiny shape like a small bone in a fish and, therefore, once it sticks in mucous membrane or the like, it is rather difficult to discharge asbestos out of a human body using the self-cleaning function of the human body.
It is said that various health disorders and diseases are brought about for this reason. It has also been indicated that asbestos inhalation causes pleural apex (pleural thickening), lung asbestos (asbestis), or emphysema, and further causes malignant mesothelioma or lung cancer. Furthermore, these disorders and diseases are said to develop 10 to 20 years later after inhalation. Therefore, countermeasures must be taken now as soon as possible.
At present, with respect to asbestos sprayed onto a ceiling or the like, after measures are taken such that workers are wrapped up in fully protective work suits and the object is enclosed with a resin sheet so as to prevent the asbestos from scattering to the surrounding areas, the asbestos sprayed onto ceiling or the like is detached from the foundation of the ceiling and then the asbestos is disposed of. However, worker safety needs to be extremely tightly controlled. Further because asbestos easily scatters in the air, the measure of preventing the asbestos from being scattered to the surrounding areas is an extremely laborious task. In addition, the asbestos thus detached and collected cannot be discarded as is and, further, asbestos is resistant to corrosion. Therefore, a permanent measure for the disposal of asbestos is required in which the health of workers and the prevention of scattering of asbestos to the surrounding areas are taken into consideration, thereby requiring much greater costs for the disposal. Of course, it is obvious that subsidiary materials and the like that are used in the disposal work should be completely disposed of.
At present, asbestos and asbestos-containing material are buried in a final landfill site as specially controlled industrial waste, but this is not without limit. For this reason, various kinds of asbestos detoxification technologies have been proposed hitherto. A representative example thereof is a melting method using a sealed electric furnace (Japanese Patent No. 3085959).
In the above document, a detoxification method is disclosed by which asbestos collected in a bag through a chute is melted at high temperature in a sealed electric furnace. An example of a further-developed method thereof is a method in which asbestos that is detached from the surface of a base material is placed in a calcium bag, and is incinerated along with the bag. However, the asbestos detoxification method, even though it employs treatment using an sealed electric furnace, requires a treatment temperature of at least 1000° C. and preferably at least 1500° C., raising the problem of enormous energy consumption, so that the method has not yet been practically applied.
On the other hand, as an asbestos detoxification method, another technique has been disclosed (Japanese Patent Application Laid-Open No. 2005-134554). In this technique, asbestos and a chlorofluorocarbon decomposition product are mixed and the resulting mixture is subjected to heat treatment so as to detoxify the asbestos. However, a large amount of powder dust is unavoidably produced when an existing asbestos layer is detached, and powder dust is also produced when the asbestos to be treated is transported or when the asbestos is mixed with the chlorofluorocarbon decomposition product. The workers and people in the surrounding areas are undeniably affected. Furthermore, the technique of decomposing chlorofluorocarbon is an extremely difficult technique and also expensive and, therefore, has a huge problem in practical application.